Rusted Maststep 41' Morgan O/I

[svensk viking]

Still working on the refitt on my morgan. Do you'all have a suggestion for this?

[svensk viking]

I should add, the metal is almost completly gone. I guess I can't ignore it.. I'd like to take metal out, grind it down and weld a new piece on. In the same hight and position...It can't be that simple would it? Please advice

[skipmac]

Is the actual step on the top where the mast sits steel as well or aluminum? Hard to tell in the photo. It looks kind of like aluminum but I do see what looks like a rust stain. If that part is steel I would replace the whole affair. If the top is aluminum I would save that and replace the whole steel part underneath.

I just did a similar repair in my boat and used a slab of UHMWPE (Ultra High Molecular Weight Ploy Ethylene). Stuff is very strong and will eliminate the problem of steel rusting in the bilges. You can buy it in various sizes and thicknesses at onlinemetals.com.

Remove the steel, cut a slab of UHMWPE the correct thickness to reach the actual stepping plate for the base of the mast. Lag screw or whatever the UHMWPE to the keel using the same holes/technique as the original steel base. Attach the aluminum step to the top.

I did add bedding compound under my base.

[skipmac]

A couple of other comments.

1. How is the base of the mast? If it is corroded as well this would be a good time to trim it back to good metal and compensate for the lost length by making the step higher by the same amount.

2. It looks like over the steel is a wood block? If so, I would replace that with UHMWPE as well.

[Tripod]

I just did this job on my OI41 in 2010. The original step is cast aluminum and the plate under it is mild steel. If there's a block of wood between the two, its likely that the mast has already been trimmed. When built, the aluminum step was mounted directly to the steel plate. Mine looked similar to yours (except for the wood block).

Now it looks like this:





Aluminum plates stacked and bolted. Then the whole assembly was glued (3M 4200) and lagged into the original holes after a light grinding and painting of the bilge. Pretty big job, but not too difficult. Good time to re-wire the mast too.

[Tripod]

This would work just as well with UHMWPE. Wish I had thought of that. Good suggestion skipmac.

[skipmac]

Originally Posted by Tripod

This would work just as well with UHMWPE. Wish I had thought of that. Good suggestion skipmac.

Thanks. Hope it works as expected. I haven't launched yet. Ask me in a couple of years if I have any regrets.

[svensk viking]

Originally Posted by Tripod

This would work just as well with UHMWPE. Wish I had thought of that. Good suggestion skipmac.

Thanks Tripod and skipmac!
Both suggestions sound really good!

[svensk viking]

The steel plate for the aluminum step has four corner bolts that attaches to something in the keel ( in my case the bolts are completly rusted away- you can barely see were they just to be)

what do those corner bolts attach too? The steel plate attach to concrete ( really..) the led starts a few feet after the step.

Would it work with concrete expansion sleeve bolts? Since I don't have anything to bolt the plate too?
Need some suggestions, please.
Skipmac and Tripod had some good ideas about the replacement of the step.
The vessel is a -72 morgan o/i 41'

[skipmac]

First a disclaimer: I am an engineer but electrical and not marine or structural so any opinions should be checked carefully with a qualified marine engineer as this system is holding up your mast and failure could result in major damage or injury on your boat.

In my boat the base plate was held in by four lag screws. The keel design is lead encapsulated in fiberglass so the lag screws holding the mast step assembly go right into the lead, no concrete to deal with.

In your case it sounds like the step is over the concrete so you have to deal with some sort of device to hold the lag screws. First you should understand that the load on the mast step is mainly a compression load, straight down to the keel. Yes there is certainly a lateral component that will push the step fore and aft and to the side but much less than the compression load. So the requirement for the strength of the screws holding the step to the keel is not that great.

So I think using lead, expandable anchors in the concrete keel would work. Are you able to probe into the old screw holes with a tool to feel the concrete around the hole to see if it feels fractured or pulverized? That would be one of the issues I would want to check.